Switching Mode Power Supply (SMPS) is widely used for converting an input voltage to an output voltage and supplying a load due to its many advantages such as high efficiency, high current carrying ability and so on. A SMPS has at least one power switch, and the output voltage is regulated at least by controlling the ON and OFF actions of the power switch. A SMPS may comprise a buck converter, a boost converter, a flyback converter and so on.
At times, a current flowing through the output stage is required to be detected. For example, when a short condition occurs, the current flowing through a power switch or another component is higher than a maximum current limit, the power switch or the component will be damaged. Accordingly the current is required to be detected for short protection.
FIG. 1 illustrates a prior art buck converter with inductor current detecting. Buck converter comprises a high-side switch 11, a low-side switch 12, an inductor 13 and an output capacitor 14. Since inductor 13 has a parasitic resistance RI, the current flowing through inductor 13 is sensed by sensing the Direct Current (DC) voltage across inductor 13 by using serially coupled resistor 15 and capacitor 16. However, this sensing method is not accurate due to the variation of inductor resistance RI. And furthermore, the sensed voltage VS across capacitor 16 changes with temperature.
Accordingly, an improved inductor current detection circuit is required to at least address one or some of the above deficiencies.